The present invention generally relates to keyless security entry control methods for motor vehicles. In particular, the present invention relates to a keyless security entry control method between a transceiver device disposed in a motor vehicle and an identification transmitter (ID-transmitter) in which determining the position of the ID-transmitter with respect to the motor vehicle coded signals indicative of specific motor vehicle regions and action signals are transmitted by the transceiver device and received by the ID-transmitter.
DE 41 23 654 A1 discloses a keyless security entry method for determining if an ID transmitter is located in the passenger compartment of the motor vehicle. The vehicle is locked if it is determined that no ID transmitters are located inside the passenger compartment. The position of the ID transmitter is determined for discovering whether the ID transmitter is located inside or outside of the vehicle. Two antennas functioning independently from each other are used to perform the disclosed method. One of the antennas is directed at the internal compartment of the vehicle and the other antenna is directed at the outside area of the vehicle (driver door region, passenger door region).
If after getting out of the vehicle an operator carrying an ID transmitter wishes to lock the vehicle by actuating the external door handle a question-response dialogue is initiated between a transceiver device within the vehicle and the ID transmitter. The ID transmitter can only transmit a response signal back to the transceiver device if the ID transmitter is located outside the vehicle in the reception range of the antenna directed at the outside area.
A plurality of ID transmitters is normally used with this type of keyless security entry control method. Therefore, the situation can arise that one ID transmitter remains in the vehicle and another ID transmitter is outside the vehicle and is used to lock the vehicle. Even if it is possible to unlock the vehicle by using one authorized ID transmitter the vehicle can be started up without authorization by using the ID transmitter remaining in the vehicle. For example, if anyone breaks into the vehicle.
This problem which arises from the method disclosed in DE 41 23 654 A1 is counteracted by the method disclosed in DE 197 35 658 C1. DE 197 35 658 C1 discloses a method in which upon detecting the operator""s desire to lock the vehicle a test signal is transmitted from the transceiver device within the vehicle to ascertain whether ID transmitters are located in the passenger compartment after the vehicle has been locked. ID transmitters located in the passenger compartment respond to this test signal. A storage device allocated to the transceiver device registers these ID transmitters and disables them on the vehicle system side as being unauthorized. This feature ensures that the ID transmitters remaining in the passenger compartment prevent the vehicle from being unlocked and prevent an associated deactivation of an electronic immobilizer if an unauthorized user gains access to this ID transmitter, e.g. by breaking into the vehicle. Only after the vehicle has been unlocked once again using an authorized ID transmitter is the registration deleted of the particular ID transmitter which had been in the passenger compartment if this ID transmitter is still located in the passenger compartment when the authorized unlocking procedure takes place.
However, even if this method prevents the direct use by unauthorized persons of the ID transmitter located in the vehicle, it is possible should anyone steal this type of ID transmitter for them to use suitable means to read the coding thereof. The obtained information can ultimately be used to simulate an authorized ID transmitter to enable theft of the vehicle.
Therefore, it is an object of the present invention to provide a generic keyless security entry control method in which operational security is improved with respect to the methods of the prior art. This object is achieved by the ID transmitter itself determining its position by evaluating signals received from a transceiver device in the motor vehicle.
In accordance with the above object and other objects, the present invention provides a keyless security entry control method and system for motor vehicles. The method includes transmitting respective coded signals from at least two transmitters. The transmitted coded signals overlap within the motor vehicle and are separated outside of the motor vehicle. The coded signals are then received from the at least two transmitters with an identification (ID) transmitter. The position of the ID transmitter with respect to the motor vehicle is then determined from the received coded signals. The position of the ID transmitter is determined to be inside of the motor vehicle if the ID transmitter receives at least two coded signals and is determined to be outside of the motor vehicle if the ID transmitter receives only one coded signal.
Preferably, the method further includes transmitting a coded signal towards the area outside of a driver side of the motor vehicle from a first transmitter and transmitting a coded signal towards the area outside of an opposite passenger side of the motor vehicle from a second transmitter. The position of the ID transmitter is determined to be outside the motor vehicle and adjacent the driver side if the ID transmitter receives only the coded signal from the first transmitter. The position of the ID transmitter is determined to be inside the motor vehicle and adjacent the passenger if the ID passenger receives only the coded signal from the second transmitter.
The method may further include transmitting an action signal from a transceiver device. The action signal being indicative of an action to be performed. In response to the ID transmitter receiving the action signal it is determined whether the position of the ID transmitter enables the ID transmitter to perform the action. If the position of the ID transmitter enables the ID transmitter to perform the action then a response signal is transmitted from the ID transmitter. The transceiver device then performs the action in response to receiving the response signal. The ID transmitter may then transmit a position signal indicative of the position of the ID transmitter. In response to receiving the position signal the transceiver device performs the action as a function of the position of the ID transmitter. The ID transmitter may be switched to a non operative mode if the position of the ID transmitter disables the ID transmitter from performing the action.
In the case of the keyless security entry control method and system of the present invention, the ID transmitter itself determines its position and evaluates further the received signals. Therefore, in contrast to the ID transmitters of the prior art, the ID transmitter of the present invention is not merely passive with respect to the determination of its position (=transponder) but can also be described as being intelligent by actively evaluating the position-coded signals. The ID transmitter evaluates the received coded signals in a first step to establish whether the ID transmitter is located inside or outside of the vehicle. As provided in one embodiment, it is possible to perform a higher resolution position determination process wherein not only is the determination process performed to establish whether the ID transmitter is located inside or outside of the vehicle but a position determination process relating to the sides of the vehicle is also performed for establishing, for example, whether the ID transmitter is located on the driver or passenger side of the vehicle.
Following on from this type of position determination process, a plausibility check with respect to the received action signal is performed, in a first step of a further evaluation of the received action signal, in dependence upon the previously determined position of the ID transmitter. This plausibility check establishes whether the ID transmitter receiving the action signal is associated with regard to its position in a plausible manner with the action which is to be triggered. If an ID transmitter is located, for example, outside the vehicle and if by actuating the external door handle the ID transmitter has communicated to the system its wish to perform the locking action, then the ID transmitter receives upon being prompted a corresponding action signal which will lock the vehicle. The ID transmitter located outside the vehicle, e.g. in the region of the driver""s door, has identified its own position by the position determination process and will conclude the plausibility check with a positive result because its ascertained position is objectively associated with the locking signal.
In contrast, if the ID transmitter or another ID transmitter is located in the internal compartment of the vehicle and receives this type of locking signal, then the plausibility check concludes with a negative result because this ID transmitter is not responsible for this type of question. A locking action will only be permitted if an authorized ID transmitter is located outside the vehicle. Following on from the plausibility check one or several actions is/are performed by the ID transmitter. In the former case, in which the ID transmitter is located outside the vehicle, the ID transmitter transmits a response signal to the transceiver device within the vehicle for locking the vehicle. In the latter case, wherein the plausibility check concludes with a negative result, the ID transmitter is immediately switched to its non-operative mode and does not take part in any further communication.
To avoid misuse of an ID transmitter located in the vehicle it is provided that during a triggered alarm an action signal is transmitted by the transceiver device within the vehicle using a prior prompting signal, whereupon the ID transmitters located in the internal compartment of the vehicle self-disable and therefore are not suitable for further use. ID transmitters which in such a case are located outside the vehicle would conclude the plausibility check with a negative result in such a case and would thus not be disabled. An ID transmitter which is disabled in this manner is also of no value to an unauthorized user within the scope of a simulation device used as a manipulator of the transceiver device. Attempts using this type of manipulator for stimulating the ID transmitter to transmit response signals fail because it is not possible to transmit response signals due to the self-disable facility in the ID transmitter. Therefore, it is not possible to use the ID transmitter for discovering a suitable simulation using a manipulator of this type.
The fact that all ID transmitters located in the transmission range of the transceiver device are prompted for a short period of time and that the ID transmitters which have concluded the plausibility check with a positive result are limited to a question-response dialogue to be performed signifies for the particular ID transmitters, which do not take part or do not need to take part in this dialogue, that they can be switched once again to their non-operative mode immediately after completing the plausibility check without corresponding current consumption.
In one embodiment of the method, it can be provided that the position determination ascertained by the ID transmitter is contained in a response telegram transmitted to the transceiver device so that the ID transmitter positions are known on the vehicle system side.
These and other features, aspects, and embodiments of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings.